Potassium hexafluoroaluminate

Potassium hexafluoroaluminate is an inorganic chemical compound with the chemical formula K3AlF6. It naturally occures as the mineral cryolite.

Synthesis
Potassium hexafluoroaluminate can be obtained by reacting fluoroaluminic acid (obtained by the reaction of anhydrous hydrogen fluoride and aluminum hydroxide) with potassium hydroxide at high temperature, followed by filtering, drying, melting, and crushing.


 * 6HF + Al(OH)3 -> AlF3*3HF + 3H2O
 * AlF3*3HF + 3KOH -> K3AlF6 + 3H2O

Physical characteristics
Potassium hexafluoroaluminate appears as a white to light grey powder, and is slightly soluble in water.

It forms colorless crystals of the tetragonal system, space group I41/a.

Uses
Potassium hexafluoroaluminate is used as a welding agent.

It is also used in the production of pesticides, manufacture of glassware and enamel industry, in addition to being a solvent for the bauxite in the electrical manufacture of aluminum.